Crown ethers are well-known for their ability to form strong complexes with alkali metal and organic cations. This unique cation binding ability has led to numerous applications in synthetical and analytical chemistry for crown ethers, for example the applications demonstrated in the following articles: "Potassium tert-Butoxide Complexed with a Macrocyclic Ligand for Determination of Autoprotolysis Constant of tert-Butanol and as a Titrant" by I. M. Kolthoff et al., J. Anal. Chem., Vol. 51, No. 8, 1301 (1979); "Preparation and properties of ion exchangers based on macrocylic polyethers" by E. Blasins, J. Chromatogr. 96, 89 (1974); and "Use of Crown Ethers in Liquid Chromatography" by K. Kimura and J. Shono, J. Liq. Chromatogr., 5 (Suppl. 2), 223-225 (1982).
Liquid Crystal is a mesophase between the crystalline (solid) and the amorphous (liquid) states. Crystal is an essentially homogenous substance in which molecules are arranged in a three-dimensional periodic pattern, i.e. a lattice, and the movement of these particles is confined in the lattice. On the other hand, liquid is an amorphous substance in which molecules have a significantly higher freedom of movement. Liquid Crystal is a mesophase between them, the molecules thereof are arranged in a one-or two-dimensional pattern and have an ability of movement similar to the liquid molecule. Therefore, a special electro-optical phenomenom may be observed when a liquid crystal is subject to an external driving force such as electric field.
Recently some authors have demonstrated the possibility of combining the complexing properties of crown ethers with the supramolecular arrangements provided by the mesophases of thermotropic liquid crystals. He et al. in their article entitled "Nematic Liquid Crystal Compounds containing a Benzocrown Ether Unit", J. Chem. Soc. Chem. Commun., 1294 (1987), reported some nematic liquid crystal containing benzocrown ether units. Percec et al. in their article entitled "Liquid Crystal Polyethers Containing Macroheterocyclic Ligands. 1. Polyethers and Copolyethers Based on 4,4'-Dihydroxy-.alpha.-methylstilbene, Bis(8-bromooctyl)dibenzo-18-crown-6, and/or 1,11-Dibromoundecane", Macromolecules, 22, 2043 (1989), presented the synthesis and characterization of the thermotropic main-chain liquid crystalline polyethers and copolyethers containing dibenzocrown ether units. Cowie et al. in their article entitled "Thermotropic Liquid Crystalline Main-chain Polyamides Containing Diaza-18-crown-6-ether Units", Brt. Polym. J., 20, 515 (1988), demonstrated the synthesis of thermotropic liquid crystalline main-chain polyamide containing diaza-18-crown-6-ether units.
The object of present invention is to provide a series of new side-chain liquid crystalline polymers containing crown ether based mesogens. As far as the best knowledge we know, this is the first example of a side-chain liquid crystalline polymers containing crown ether based mesogens.